Yet according to industry standards, a regular portion of fish should weigh just 170g while chips should be 284g.

And people want these standards enforced more heavily.

Tom Pickerell, technical director at industry body Seafish, said standard portion sizes would have two main benefits.

He said: ‘Firstly by standardising portion sizes across the industry, consumers will know what to expect when ordering their selected portion size, wherever they are in the UK.

‘Secondly, it’s about choice. By offering a greater selection of sizes, shops can potentially open themselves up to increased business from lunch time trade and by upselling to single smaller portions, rather than a larger shared portion.’

By standardising portion sizes, it will also help to cut waste, improve profits and provide clearer nutrition information, the Agriculture and Horticulture Development Board (AHDB) said.

Rob Clayton, of the AHDB, said: ‘A key finding of the research was that one in three people said a greater range of portion sizes would encourage them to eat fish and chips more often.

‘That’s more than 17 million people across the UK.

‘Couple this with the fact that 45% of people would order smaller portions to cut their calorie intake and there is a huge marketplace for outlets to encourage health conscious consumers through their doors.’